In a principal aspect the present invention relates to a fluid logic device and more particularly to a sequential AND.
It is often desirable to provide a sequential logic system to control pneumatically operated equipment for example. Various fluid logic devices have been proposed and are disclosed in prior publications, e.g. Bouteille, Fluid Logic Devices, John Wiley and Sons. Additionally, many patents have issued which teach various devices and systems including the patent to Brandenberg for an AND device, U.S. Pat. No. 3,385,322, issued May 28, 1968.
Fluid logic systems which provide for sequential operations such as flip-flop systems are very complex if conventional control hardware and techniques such as disclosed in Bouteille and the Brandenberg patent referenced above are utilized. Complex systems such as disclosed in the prospective patent application identified by Ser. No. 63,923 filed Aug. 6, 1979, entitled "Multiple Element Fluid Logic Controls", Brandenberg, inventor, require a multitude of logic elements in order to provide the desired sequential operation. To reduce the number of logic elements in such systems therefore, sequential fluid logic devices become desirable.
One of the desired fluid logic elements useful in sequential systems is a sequential AND device. Such a device would include a first input (a) and a second input (b) as well as an output (c). An output signal would be provided only in the event of a proper sequence of signals to the inputs (a) and (b).